Is Intelligent Design Testable?

William A. Dembski
01.24.01

Eugenie Scott is a physical anthropologist who as director of the National
Center for Science Education travels the United States warning audiences about
the threat of creationism and unmasking its various guises. Intelligent design,
according to her, is currently the most sinister of these guises. Scott has
developed a standard shtick, which includes not only some well-worn arguments
against creationism and some newer arguments against intelligent design (which
she refers to as "neocreationism") but also some comedic elements,
like the Monty Python wink-wink-nudge-nudge routine, which she uses when she
wants to make clear to her audiences that the designer of intelligent design
is really none other than the "Big G" of the Christian faith.

Recently (January 18, 2001) Scott presented a lecture at U.C. Berkeley sponsored
by the department of integrative biology and titled "Icons of Creationism:
The New Anti-Evolutionism and Science" (http://ib.berkeley.edu/seminars/index.html).
The title alludes to Jonathan Wells's recent book _Icons of Evolution_, which
critiques the various standard evidences used in textbooks to support Darwinian
evolution. Scott presumably means to turn the tables and show that intelligent
design is similarly open to criticism.

Scott's key criticism against intelligent design, both in her talk the other
day and since the early nineties, has been that intelligent design is untestable.
For instance, in an exchange with Stephen Meyer back in 1994 in _Insight_ magazine,
Scott remarked that until design theorists develop a "theo-meter"
(this neologism is hers) to test for design, they are treading water in a sea
of retarded scientific aspirations. In her talk the other day at U.C. Berkeley
she claimed that intelligent design does not propose any "testable model."

The testability objection to intelligent design can be interpreted in two ways.
One is to claim that intelligent design is in principle untestable. This seems
to have been Scott's line in the early nineties. Certainly it is a hallmark
of science that any of its claims be subject to revision or refutation on the
basis of new evidence or further theoretical insight. If this is what one means
by testability, then design is certainly testable. Indeed, it was in this sense
that Darwin tested William Paley's account of design and found it wanting. It
simply won't wash to say that design isn't testable and then in the same breath
say that Darwin tested design and refuted it.

The other way to interpret the testability objection is to claim that intelligent
design may in principle be testable, but that no tests have been proposed to
date. This seems to be Scott's line currently. Indeed, if the testability objection
is to bear any weight, its force must reside in the absence of concrete proposals
for testing intelligent design. Are such proposals indeed lacking? Rather than
looking solely at the testability of intelligent design, I want also to consider
the testability of Darwinism. By comparing the testability of the two theories,
it will become evident that even the more charitable interpretation of Scott's
testability objection does not hold up.

In relation to science testability is a very broad notion. It certainly includes
Karl Popper's notion of falsifiability, but it is hardly coextensive with it
and can apply even if falsifiability does not obtain. Testability as well covers
confirmation, predicability, and explanatory power. At the heart of testability
is the idea that our scientific theories must make contact with and be sensitive
to what's happening in nature. What's happening in nature must be able to affect
our scientific theories not only in form and content but also in the degree
of credence we attach to or withhold from them. For a theory to be immune to
evidence from nature is a sure sign that we're not dealing with a scientific
theory.

What then are we to make of the testability of both intelligent design and
Darwinism taken not in a generic abstract sense but concretely? What are the
specific tests for intelligent design? What are the specific tests for Darwinism?
And how do the two theories compare in terms of testability? To answer these
questions, let's run through several aspects of testability, beginning with
falsifiability.

FALSIFIABILITY: Is intelligent design falsifiable? Is Darwinism falsifiable?
Yes to the first question, no to the second. Intelligent design is eminently
falsifiable. Specified complexity in general and irreducible complexity in biology
are within the theory of intelligent design the key markers of intelligent agency.
If it could be shown that biological systems like the bacterial flagellum that
are wonderfully complex, elegant, and integrated could have been formed by a
gradual Darwinian process (which by definition is non-telic), then intelligent
design would be falsified on the general grounds that one doesn't invoke intelligent
causes when purely natural causes will do. In that case Occam's razor finishes
off intelligent design quite nicely.

On the other hand, falsifying Darwinism seems effectively impossible. To do
so one must show that no conceivable Darwinian pathway could have led to a given
biological structure. What's more, Darwinists are apt to retreat into the murk
of historical contingency to shore up their theory. For instance, Allen Orr
in his critique of Behe's work shortly after _Darwin's Black Box_ appeared remarked,
"We have no guarantee that we can reconstruct the history of a biochemical
pathway." What he conceded with one hand, however, he was quick to retract
with the other. He added, "But even if we can't, its irreducible complexity
cannot count against its gradual evolution."

The fact is that for complex systems like the bacterial flagellum no biologist
has or is anywhere close to reconstructing its history in Darwinian terms. Is
Darwinian theory therefore falsified? Hardly. I have yet to witness one committed
Darwinist concede that any feature of nature might even in principle provide
countervailing evidence to Darwinism. In place of such a concession one is instead
always treated to an admission of ignorance. Thus it's not that Darwinism has
been falsified or disconfirmed, but that we simply don't know enough about the
biological system in question and its historical context to determine how the
Darwinian mechanism might have produced it.

For instance, to neutralize the challenge that the irreducible complexity of
the bacterial flagellum raises against Darwinism, Ken Miller employs the following
argument from ignorance. Like the rest of the biological community, Miller doesn't
know how the bacterial flagellum originated. The biological community's ignorance
about the flagellum, however, doesn't end with its origin but extends to its
very functioning. For instance, according to David DeRosier, "The mechanism
of the flagellar motor remains a mystery." Miller takes this admission
of ignorance by DeRosier and uses it to advantage. In _Finding Darwin's God_
he writes: "Before [Darwinian] evolution is excoriated for failing to explain
the evolution of the flagellum, I'd request that the scientific community at
least be allowed to figure out how its various parts work." But in the
article by DeRosier that Miller cites, Miller conveniently omits the following
quote: "More so than other motors, the flagellum resembles a machine designed
by a human."

So apparently we know enough about the bacterial flagellum to know that it
is designed or at least design-like. Indeed, we know what most of its individual
parts do. Moreover, we know that the flagellum is irreducibly complex. Far from
being a weakness of irreducible complexity as Miller suggests, it is a strength
of the concept that one can determine whether a system is irreducibly complex
without knowing the precise role that each part in the system plays (one need
only knock out individual parts and see if function is preserved; knowing what
exactly the individual parts do is not necessary). Miller's appeal to ignorance
obscures just how much we know about the flagellum, how compelling the case
is for its design, and how unfalsifiable Darwinism is when Darwinists proclaim
that the Darwinian selection mechanism can account for it despite the absence
of any identifiable biochemical pathway.

CONFIRMATION: What about positive evidence for intelligent design and Darwinism?
From the design theorist's perspective, the positive evidence for Darwinism
is confined to small-scale evolutionary changes like insects developing insecticide
resistance. This is not to deny large-scale evolutionary changes, but it is
to deny that the Darwinian mechanism can account for them. Evidence like that
for insecticide resistance confirms the Darwinian selection mechanism for small-scale
changes, but hardly warrants the grand extrapolation that Darwinists want. It
is a huge leap going from insects developing insecticide resistance via the
Darwinian mechanism of natural selection and random variation to the very emergence
of insects in the first place by that same mechanism.

Darwinists invariably try too minimize the extrapolation from small-scale to
large-scale evolution, arguing that it is a failure of imagination on the part
of critics to appreciate the wonder-working power of the Darwinian mechanism.
From the design theorist's perspective, however, this is not a case of failed
imagination but of the emperor's new clothes. Yes, there is positive evidence
for Darwinism, but the strength and relevance of that evidence on behalf of
large-scale evolution is very much under dispute, if not within the Darwinian
community then certainly outside of it.

What about the positive evidence for intelligent design? It seems that here
we may be getting to the heart of Eugenie Scott's concerns. I submit that there
is indeed positive evidence for intelligent design. To see this, let's consider
an example that I recycle endlessly in my writings (if only because its force
seems continually lost on Darwinists). Consider the movie _Contact_ that appeared
summer of 1997, based on the novel by Carl Sagan. In the movie radio astronomers
determine that they have established contact with an extraterrestrial intelligence
after they receive a long sequence of prime numbers, represented as a sequence
of bits.

Although in the actual SETI program (Search for Extraterrestrial Intelligence)
radio astronomers look not for something as flamboyant as prime numbers but
something much more plebeian, namely, a narrow bandwidth of transmissions (as
occur with human radio transmissions), the point nonetheless remains that SETI
researchers would legitimately count a sequence of prime numbers (and less flamboyantly
though just as assuredly a narrow bandwidth transmission) as positive evidence
of extraterrestrial intelligence. No such conclusive signal has yet been observed,
but I can assure you that if it were to be observed, Eugenie Scott would not
be complaining about SETI not having proposed any "testable models."
Instead she would rejoice that the model had been tested and decisively confirmed.

Now what's significant about a sequence of prime numbers from outer space is
that they exhibit specified complexity -- there has to be a long sequence (hence
complexity) and it needs to display an independently given pattern (hence specificity).
But what if specified complexity is also exhibited in actual biological systems?
In fact it is -- notably in the bacterial flagellum. Internet mavens have been
pestering me for actual calculations of complexity involved in such systems.
I address this in my forthcoming book (_No Free Lunch_), but such calculations
are out there in the literature (cf. the work of Hubert Yockey, Robert Sauer,
Peter Rüst, Paul Erbrich, Siegfried Scherer, and most recently Douglas
Axe -- I'm not enlisting these individuals as design advocates but merely pointing
out that methods for determining specified complexity are already part of biology).

Even so, it appears that Eugenie Scott would not be entirely happy admitting
that intelligent design is positively confirmed once some clear-cut instances
of specified complexity are discovered in biological systems. Why not? As she
put it in her U.C. Berkeley lecture, design theorists "never tell you what
happened." Well, neither do SETI researchers. If a SETI researcher discovers
a radio transmission of prime numbers from outer space, the inference to an
extraterrestrial intelligence is clear, but the researcher doesn't know "what
happened" in the sense of knowing any details about the radio transmitter
or for that matter the extraterrestrial that transmitted the radio transmission.

Ah, but we have experience with radio transmitters. At least with extraterrestrial
intelligences we can guess what might have happened. But we don't have any experience
with unembodied designers, and that's clearly what we're dealing with when it
comes to design in biology. Actually, if an unembodied designer is responsible
for biological complexity, then we do have quite a bit of experience with such
a designer through the designed objects (not least ourselves) that confront
us all the time. On the other hand, it is true that we possess very little insight
at this time into how such a designer acted to bring about the complex biological
systems that have emerged over the course of natural history.

Darwinists take this present lack of insight into the workings of an unembodied
designer not as remediable ignorance on our part and not as evidence that the
designer's capacities far outstrip ours, but as proof that there is no unembodied
designer (at least none relevant to biology). By the same token, if an extraterrestrial
intelligence communicated via radio signals with earth and solved computational
problems that exceeded anything an ordinary or quantum computer could ever solve,
we would have to conclude that we weren't really dealing with an intelligence
because we have no experience of super-mathematicians that can solve such problems.
My own view is that with respect to biological design humans are in the same
position as William James's dog studying James while James was reading a book
in his library. Our incomprehension over biological design is the incomprehension
of a dog trying to understand its master's actions. Interestingly, the biological
community regularly sings the praises of natural selection and the wonders it
has wrought while admitting that it has no comprehension of how those wonders
were wrought. Natural selection, we are assured, is cleverer than we are or
can ever hope to be. Darwinists have merely swapped one form of awe for another.
They've not eliminated it.

It is no objection at all that we don't at this time know how an unembodied
designer produced a biological system that exhibits specified complexity. We
know that specified complexity is reliably correlated with the effects of intelligence.
The only reason to insist on looking for non-telic explanations to explain the
complex specified structures in biology is because of prior commitment to naturalism
that perforce excludes unembodied designers. It is illegitimate, scientifically
and rationally, to claim on a priori grounds that such entities do not exist,
or if they do exist that they can have no conceivable relevance to what happens
in the world. Do such entities exist? Can they have empirical consequences?
Are they relevant to what happens in the world? Such questions cannot be prejudged
except on metaphysical grounds. To prejudge these questions the way Eugenie
Scott does is therefore to make certain metaphysical commitments about what
there is and what has the capacity to influence events in the world. Such commitments
are utterly gratuitous to the practice of science. Specified complexity confirms
design regardless whether the designer responsible for it is embodied or unembodied.

PREDICTABILITY: Another aspect of testability is predictability. A good scientific
theory, we are told, is one that predicts things. If it predicts things that
don't happen, then it is tested and found wanting. If it predicts things that
do happen, then it is tested and regarded as successful. If it doesn't predict
things, however, what then? Often with theories that try to account for features
of natural history, prediction gets generalized to include retrodiction, in
which a theory also specifies what the past should look like. Darwinism is said
to apply retrodictively to the fossil record and predictively in experiments
that place an organism under selection pressures and attempt to induce some
adaptive change.

But in fact Darwinism does not retrodict the fossil record. Natural selection
and random variation applied to single-celled organisms offers no insight at
all into whether we can expect multi-celled organisms, much less whether evolution
will produce the various body-plans of which natural history has left us a record.
At best one can say that there is consilience, i.e., that the broad sweep of
evolutionary history as displayed in the fossil record is consistent with Darwinian
evolution. Design theorists strongly dispute this as well (pointing especially
to the Cambrian explosion). But detailed retrodiction and detailed prediction
are not virtues of Darwin's theory. Organisms placed under selection pressures
either adapt or go extinct. Except in the simplest cases where there is, say,
some point mutation that reliably confers antibiotic resistance on a bacterium,
Darwin's theory has no way of predicting just what sorts of adaptive changes
will occur. "Adapt or go extinct" is not a prediction of Darwin's
theory but an axiom that can be reasoned out independently.

Challenging me in _American Outlook_ biologist Alex Duncan remarked: "A
scientific theory makes predictions about the world around us, and enables us
to ask and answer meaningful questions. For example, we might pose the question
'why do polar bears have fur, while penguins have feathers, given the similar
nature of their environments

Evolution provides an answer to this question. The only answer creationism (or
intelligent design) provides is 'because God made them that way.'" Actually,
evolution, whether Darwinian or otherwise, makes no predictions about there
being bears or birds at all or for that matter bears having fur and birds having
feathers. Once bears or birds are on the scene, they need to adapt to their
environment or die. Intelligent design can accommodate plenty of evolutionary
change and allows for natural selection to act as a conservative force to keep
organisms adapted to their environments. Contrary to Duncan's remark, intelligent
design does not push off all explanation to the inscrutable will of God. On
the other hand, intelligent design utterly rejects natural selection as a creative
force capable of bringing about the specified complexity we see in organisms.

It's evident, then, that Darwin's theory has virtually no predictive power.
Insofar as it offers predictions, they are either extremely general, concerning
the broad sweep of natural history and in that respect quite questionable (Why
else would Stephen Jay Gould and Niles Eldredge need to introduce punctuated
equilibria if the fossil record were such an overwhelming vindication of Darwinism?);
and when the predictions are not extremely general they are extremely specific
and picayune, dealing with small-scale adaptive changes. Newton was able to
predict the path that a planet traces out. Darwin's disciples can neither predict
nor retrodict the pathways that organisms trace out in the course of natural
history.

But what about the predictive power of intelligent design? To require prediction
fundamentally misconstrues design. To require prediction of design is to put
design in the same boat as natural laws, locating their explanatory power in
an extrapolation from past experience. This is to commit a category mistake.
To be sure, designers, like natural laws, can behave predictably (designers
often institute policies that end up being rigidly obeyed). Yet unlike natural
laws, which are universal and uniform, designers are also innovators. Innovation,
the emergence to true novelty, eschews predictability. Designers are inventors.
We cannot predict what an inventor would do short of becoming that inventor.
Intelligent design offers a radically different problematic for science than
a mechanistic science wedded solely to undirected natural causes. Yes, intelligent
design concedes predictability. But this represents no concession to Darwinism,
for which the minimal predictive power that it has can readily be assimilated
to a design-theoretic framework.

EXPLANATORY POWER: According to Darwin the great advantage of his theory over
William Paley's theory of design was that Darwin's theory managed to account
for a wide diversity of biological facts that Paley's theory could not. Darwin's
theory was thus thought to have greater explanatory power than Paley's , and
this relative advantage could be viewed as a test of the two theories. Underlying
explanatory power is a view of explanation known as inference to the best explanation
in which a "best explanation" always presupposes at least two competing
explanations and attempts to determine which comes out on top. Design theorists
see advances in the biological and information sciences as putting design back
in the saddle and enabling it to outperform Darwinism, thus making design currently
the best explanation biological complexity. Darwinists of course see the matter
quite differently.

What I want to focus on here, however, is not the testing of Darwinism and
design against the broad body of biological data, but the related question of
which theory can accommodate the greater range of biological possibilities.
Think of it this way: Are there things that might occur in biology for which
a design-theoretic framework could give a better, more accurate account than
a purely Darwinian and therefore non-teleological framework? The answer is yes.

First off, let's be clear that design can accommodate all the results of Darwinism.
Intelligent design does not repudiate the Darwinian mechanism. It merely assigns
it a lower status than Darwinism does. The Darwinian mechanism does operate
in nature and insofar as it does, design can live with its deliverances. Even
if the Darwinian mechanism could be shown to do all the design work for which
design theorists want to invoke design (say for the bacterial flagellum), a
design-theoretic framework would not destroy any valid findings of science.
To be sure, design would then become superfluous, but it would not become contradictory
or self-refuting.

The same cannot be said for Darwinism and the naturalism it embodies as a framework
for science. Suppose I were a super-genius molecular biologist, and I invented
some hitherto unknown molecular machine, far more complicated and marvelous
than the bacterial flagellum. Suppose further I inserted this machine into a
bacterium, set this genetically modified organism free, allowed it to reproduce
in the wild, and destroyed all evidence of my having created the molecular machine.
Suppose, for instance, the machine is a stinger that injects other bacteria
and explodes them by rapidly pumping them up with some gas (I'm not familiar
with any such molecular machine in the wild), thereby allowing the bacteria
endowed with my invention to consume their unfortunate prey.

Now let's ask the question, If a Darwinist came upon this bacterium with the
novel molecular machine in the wild, would that machine be attributed to design
or to natural selection? When I presented this example to David Sloan Wilson
at a conference at MIT two years ago, he shrugged it off and remarked that natural
selection created us and so by extension also created my novel molecular machine.
But of course this argument won't wash since the issue is whether natural selection
could indeed create us. What's more, if Darwinists came upon my invention of
a novel molecular machine inserted into a bacterium that allows it to feed on
other bacteria, they wouldn't look to design but would reflexively turn to natural
selection. But, if we go with the story, I designed the bacterial stinger and
natural selection had nothing to do with it. Moreover, intelligent design would
confirm the stinger's design whereas Darwinism never could. It follows that
a design-theoretic framework could account for biological facts that would forever
remain invisible within a Darwinian framework. It seems to me that this possibility
constitutes a joint test of Darwinism and intelligent design that strongly supports
intelligent design -- if not as the truth then certainly as a live possible
theoretical option that must not be precluded for a priori philosophical reasons
like naturalism.

In conclusion, there is no merit to Eugenie Scott's claim that intelligent
design is untestable or hasn't put forward any "testable models."
Intelligent design's claims about specified and irreducible complexity are in
close contact with the data of biology and open to refutation as well as confirmation.
What's more, as a framework for doing science intelligent design is more robust
and sensitive to the possibilities that nature might actually throw our way
than Darwinism, which must view everything through the lens of chance and necessity
and take a reductive approach to all signs of teleology in nature.

But isn't intelligent design just a stone's throw from fundamentalist Christianity
and rabid creationism? Even if a theory of intelligent design should ultimately
prove successful and supersede Darwinism, it would not follow that the designer
posited by this theory would have to be the Christian God or for that matter
be real in some ontological sense. One can be an anti-realist about science
and simply regard the designer as a regulative principle -- a conceptually useful
device for making sense out of certain facts of biology -- without assigning
the designer any weight in reality. Wittgenstein, for instance, regarded the
theories of Copernicus and Darwin not as true but as "fertile new points
of view."

Ultimately, the main question that confronts scientists working on a theory
of intelligent design is whether design provides powerful new insights and fruitful
avenues of research. The metaphysics underlying such a theory, and in particular
the ontological status of the designer, can then be taken up by philosophy and
theology. Indeed, one's metaphysics ought to be a matter of indifference to
one's scientific theorizing about design. The fact that it is not for Eugenie
Scott says more about her own biases than about the biases of design theorists,
whose primary task is to explore the fruitfulness of design for science. Yes,
we've got our work cut out for us. But instead of facilitating that work, Scott
and her National Center for Science Education are far more interested in exiling
that work to oblivion. Fortunately, design theorists have suffered exile for
so long at the hands of Darwinists that we've learned to operate effectively
even in oblivion.